001package org.apache.turbine.pipeline;
002
003
004/*
005 * Licensed to the Apache Software Foundation (ASF) under one
006 * or more contributor license agreements.  See the NOTICE file
007 * distributed with this work for additional information
008 * regarding copyright ownership.  The ASF licenses this file
009 * to you under the Apache License, Version 2.0 (the
010 * "License"); you may not use this file except in compliance
011 * with the License.  You may obtain a copy of the License at
012 *
013 *   http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing,
016 * software distributed under the License is distributed on an
017 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
018 * KIND, either express or implied.  See the License for the
019 * specific language governing permissions and limitations
020 * under the License.
021 */
022
023
024import java.io.IOException;
025
026import org.apache.turbine.util.TurbineException;
027
028/**
029 * <p>A <b>ValveContext</b> is the mechanism by which a Valve can trigger the
030 * execution of the next Valve in a Pipeline, without having to know anything
031 * about the internal implementation mechanisms.  An instance of a class
032 * implementing this interface is passed as a parameter to the
033 * <code>Valve.invoke()</code> method of each executed Valve.</p>
034 *
035 * <p><strong>IMPLEMENTATION NOTE</strong>: It is up to the implementation of
036 * ValveContext to ensure that simultaneous requests being processed (by
037 * separate threads) through the same Pipeline do not interfere with each
038 * other's flow of control.</p>
039 *
040 * @author Craig R. McClanahan
041 * @author Gunnar Rjnning
042 * @author Peter Donald
043 * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
044 * @version $Revision$ $Date$
045 */
046@FunctionalInterface
047public interface ValveContext
048{
049    /**
050     * <p>Cause the <code>invoke()</code> method of the next Valve
051     * that is part of the Pipeline currently being processed (if any)
052     * to be executed, passing on the specified request and response
053     * objects plus this <code>ValveContext</code> instance.
054     * Exceptions thrown by a subsequently executed Valve will be
055     * passed on to our caller.</p>
056     *
057     * <p>If there are no more Valves to be executed, execution of
058     * this method will result in a no op.</p>
059     *
060     * @param pipelineData The run-time information, including the servlet
061     * request and response we are processing.
062     *
063     * @throws IOException Thrown by a subsequent Valve.
064     * @throws TurbineException Thrown by a subsequent Valve.
065     * @throws TurbineException No further Valves configured in the
066     * Pipeline currently being processed.
067     */
068    void invokeNext(PipelineData pipelineData)
069        throws IOException, TurbineException;
070}